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Tuesday, October 13, 2015

"Sharktober"

I've heard of a few Great White Shark (Carcharodon carcharias) attacks on marine mammals during the last few weeks — off Half Moon Bay, between Bodega Head and Bodega Rock, from the Farallon Islands, and next to the Alcatraz Island pier.

Yesterday I encountered the probable remains of a white shark attack washed up on a local beach. It was half of a sea lion. For those interested, I'll show a picture below. (If you'd rather not see a half-eaten sea lion, then read no further.)First I'll show the tooth of a Great White Shark that I found in 2005. I posted this image in 2012. I'll admit, when I found this tooth 10 years ago, I had no idea exactly how rare it was to find a white shark tooth. I was new to California, but knew white sharks occurred in this area, so I naively thought, "Nice! A shark tooth!" And now I'd say, "WOW! A SHARK TOOTH!" I'll show the sea lion picture after the tooth.

Okay, here's the sea lion —
likely cut in half by a shark:

When I first noticed this animal from a distance, I was viewing it head-on and observed the silvery color. I thought it might have been a harbor seal. As I approached it, I noticed the long flipper and realized it was a sea lion. I hadn't known sea lions could look so silvery (I generally think of them as quite brown), but I read that the fur of younger animals can be this color after a molt.

Relatively recent research on white shark movements in this area has revealed that sharks spend time near the Central California coast in late summer/fall (primarily September-November), then migrate 2000-5000 km offshore (primarily from April-July).

If you'd like to learn more about these impressive migrations, you can read more here: